//计算1/1-1/2+1/3-1/4+1/5 …… + 1/99 - 1/100 的值
public class Test {
    public static void main(String[] args) {
        double sum = 0;
        for (int i = 1; i <= 100; i++) {
            if(i%2==0) {
                sum = sum - (1.0/i);
            }else {
                sum = sum + (1.0/i);
            }
        }
        System.out.println(sum);
    }
}
